Molecular modelling encompasses theoretical and computational methods used to model molecular behavior. It involves computational drug design, computational biology, and materials science. Virtual screening is a computational technique used in drug discovery to search small molecule libraries and identify structures most likely to bind to targets like drug receptors and enzymes. Virtual screening can dock small molecules into known protein structures and automatically evaluate large libraries to find potential drug candidates. It has advantages of being reliable, cost-effective, time-saving, and increasing success rates. Virtual screening methods include ligand-based, structure-based, and hybrid approaches.

1. Molecular modelling
VIVEK YADAV
DPSRU DELHI

2. Molecular modelling
Molecular modelling encompasses all methods,
theoretical and computational, used to model or
mimic the behaviour of molecules.
The methods involves-
Computational drug design
computational biology
materials science

3. Virtual screening
Virtual screening (VS) is a computational
technique used in drug discovery to search libraries
of small molecules
 Identify those structures which are most likely to
bind
• drug target
• protein receptor
• enzyme.

4. Virtual screening
• The virtual screening approach for docking small
molecules into a known protein structure
• Virtual screening is a process of automatic
evaluation of very large libraries of chemical
compounds and chemical structures and software in
order to determine possible drug candidates.
• The use of complementary experimental and
informatics techniques increases the chance of
success in many stages of the discovery process.

5. Virtual screening
ADVANTAGES
Virtual screening technique for the discovery of lead
compounds advantages –
• reliable,
• cost-effective
• time-saving
• delivering new drug candidates
• increases the chance of success (complementary
experimental and informatics techniques)

6. Virtual screening
methods
Methods
• Ligand-based
• Structure-based
• Hybrid methods

7. Virtual screening
Ligand-based method
Pharmacophore Models
• ligands that binds to a receptor, a model of the receptor can be built
by exploiting the collective information contained in such set of
ligands.
Ligand
• A candidate ligand can then be compared to the pharmacophore
model to determine whether it is compatible with it and therefore
likely to bind.
Ligand-based Virtual Screening
• use 2D chemical similarity analysis method.
A popular approach to ligand-based virtual screening is based on
searching molecules with shape similar to that of known actives, as
such molecules will fit the target's binding site and hence will be
likely to bind the target.

8. Virtual screening
structure -based method
• Docking of candidate ligands into a protein target
• Dock score/energy profile

9. APPLICATION
Molecular docking
To develop accurate models that could help in the drug
design of biologically active compounds
Helps in determining the important features of
structures.
Docking and analysis, SBDD and LBDD
Homology design, to understand structure of protein
Design the pharmacophore
Understand the enzyme mechanism.